3 Table of Contents – pages iv-vUnit 1: What is Biology?Chapter 1: Biology: The Study of LifeUnit 2: EcologyChapter 2: Principles of EcologyChapter 3: Communities and BiomesChapter 4: Population BiologyChapter 5: Biological Diversity and ConservationUnit 3: The Life of a CellChapter 6: The Chemistry of LifeChapter 7: A View of the CellChapter 8: Cellular Transport and the Cell CycleChapter 9: Energy in a CellTable of Contents – pages iv-v

10 What You’ll LearnYou will recognize why organisms need a constant supply of energy and where that energy comes from.You will identify how cells store and release energy as ATP.You will describe the pathways by which cells obtain energy.Chapter Intro-page 220

11 What You’ll LearnYou will compare ATP production in mitochondria and in chloroplasts.Chapter Intro-page 220

13 Section 9.1 Summary – pages 221-224Cell EnergyAll living organisms must be able to obtain energy from the environment in which they live.Plants and other green organisms are able to trap the light energy in sunlight and store it in the bonds of certain molecules for later use.Section 9.1 Summary – pages

15 Section 9.1 Summary – pages 221-224Work and the need for energyActive transport, cell division, movement of flagella or cilia, and the production, transport, and storage of proteins are some examples of cell processes that require energy.There is a molecule in your cells that is a quick source of energy for any organelle in the cell that needs it.Section 9.1 Summary – pages

16 Section 9.1 Summary – pages 221-224Work and the need for energyThe name of this energy molecule is adenosine triphosphate or ATP for short.ATP is composed of an adenosine molecule with three phosphate groups attached.Section 9.1 Summary – pages

18 Section 9.1 Summary – pages 221-224Forming and Breaking Down ATPWhen only one phosphate group bonds, a small amount of energy is required and the chemical bond does not store much energy. This molecule is called adenosine monophosphate (AMP).When a second phosphate group is added, more energy is required to force the two groups together. This molecule is called adenosine diphosphate, or ADP.Section 9.1 Summary – pages

19 Section 9.1 Summary – pages 221-224Forming and Breaking Down ATPAn even greater amount of energy is required to force a third charged phosphate group close enough to the other two to form a bond. When this bond is broken, energy is released.Section 9.1 Summary – pages

21 Section 9.1 Summary – pages 221-224How cells tap into the energy stored in ATPWhen ATP is broken down and the energy is released, the energy must be captured and used efficiently by cells.Many proteins have a specific site where ATP can bind.Section 9.1 Summary – pages

22 Section 9.1 Summary – pages 221-224How cells tap into the energy stored in ATPThen, when the phosphate bond is broken and the energy released, the cell can use the energy for activities such as making a protein or transporting molecules through the plasma membrane.ATPProteinPEnergyADPADPSection 9.1 Summary – pages

23 Section 9.1 Summary – pages 221-224How cells tap into the energy stored in ATPWhen ATP has been broken down to ADP, the ADP is released from the binding site in the protein and the binding site may then be filled by another ATP molecule.Section 9.1 Summary – pages

24 Question 1What is the primary difference in the ways that plants and animals obtain energy?AnswerAll living organisms need energy. Plants can trap light energy in sunlight and store it for later use. Animals cannot trap energy from sunlight and must eat plants that contain stored energy.NC: 4.02Section 1 Check

26 One molecule of ATP contains three phosphate groups, which are charged particles. Energy is required to bond the phosphate groups onto the same molecule because they behave the same way that the poles of magnets do and repel groups with like charges. When the ATP molecule is broken down, the chemical energy stored in it becomes available to the cell for life processes.NC: 4.02Section 1 Check

27 Question 3A molecule of adenosine that has one phosphate group bonded to it is ______.A. AMPB. ADPC. ATPD. ACPNC: 4.02Section 1 Check

29 Question 4What is the function of the protein molecule shown in this diagram?ATPProteinPEnergyADPADPNC: 4.02Section 1 Check

30 This protein molecule has a specific binding site for ATPThis protein molecule has a specific binding site for ATP. In order to access the energy stored ATP, the protein molecule binds the ATP and uncouples one phosphate group. This action releases energy that is then available to the cell.ATPProteinPEnergyADPADPNC: 4.02Section 1 Check

33 Section 9.2 Summary – pages 225-230Trapping Energy from SunlightPhotosynthesis happens in two phases.The light-dependent reactions convert light energy into chemical energy.2. The molecules of ATP produced in the light-dependent reactions are then used to fuel the light-independent reactions that produce simple sugars.The general equation for photosynthesis is written as 6CO2 + 6H2O→C6H12O6 + 6O2Section 9.2 Summary – pages

35 Section 9.2 Summary – pages 225-230The chloroplast and pigmentsTo trap the energy in the sun’s light, the thylakoid membranes contain pigments, molecules that absorb specific wavelengths of sunlight.Although a photosystem contains several kinds of pigments, the most common is chlorophyll.Chlorophyll absorbs most wavelengths of light except green.Section 9.2 Summary – pages

36 Section 9.2 Summary – pages 225-230Light-Dependent ReactionsAs sunlight strikes the chlorophyll molecules in a photosystem of the thylakoid membrane, the energy in the light is transferred to electrons.These highly energized, or excited, electrons are passed from chlorophyll to an electron transport chain, a series of proteins embedded in the thylakoid membrane.Section 9.2 Summary – pages

38 Section 9.2 Summary – pages 225-230Light-Dependent ReactionsThis “lost” energy can be used to form ATP from ADP, or to pump hydrogen ions into the center of the thylakoid disc.Electrons are re-energized in a second photosystem and passed down a second electron transport chain.Section 9.2 Summary – pages

39 Section 9.2 Summary – pages 225-230Light-Dependent ReactionsThe electrons are transferred to the stroma of the chloroplast. To do this, an electron carrier molecule called NADP is used.NADP can combine with two excited electrons and a hydrogen ion (H+) to become NADPH.NADPH will play an important role in the light-independent reactions.Section 9.2 Summary – pages

40 Section 9.2 Summary – pages 225-230Restoring electronsTo replace the lost electrons, molecules of water are split in the first photosystem. This reaction is called photolysis.Sun_1ChlorophyllO2 + 2H+2_2e-1H2O ®2H+ +O2 + 2e-H2O2Section 9.2 Summary – pages

41 Section 9.2 Summary – pages 225-230Restoring electronsThe oxygen produced by photolysis is released into the air and supplies the oxygen we breathe.The electrons are returned to chlorophyll.The hydrogen ions are pumped into the thylakoid, where they accumulate in high concentration.Section 9.2 Summary – pages

46 Section 9.2 Summary – pages 225-230The Calvin CycleSugar production One out of every six molecules of PGAL is transferred to the cytoplasm and used in the synthesis of sugars and other carbohydrates. After three rounds of the cycle, six molecules of PGAL are produced.(PGAL)(Sugars and other carbohydrates)Section 9.2 Summary – pages

47 Section 9.2 Summary – pages 225-230The Calvin CycleRuBP is replenished Five molecules of PGAL, each with three carbon atoms, produce three molecules of the five-carbon RuBP. This replenishes the RuBP that was used up, and the cycle can continue.ADP+PATP(PGAL)Section 9.2 Summary – pages

51 SunThe answer is A. The light-dependent reactions transfer energy from the sun to chlorophyll, and pass energized electrons to proteins embedded in the thylakoid membrane for storage in ATP and NADPH molecules.Light energy transfers to chlorophyll.Chlorophyll passes energy down through the electron transport chain.Energized electrons provide energy thatsplitsH2ObondsPto ADPforming ATPH+oxygenreleasedNADP+NADPHfor the use in light-independent reactionsNC: 4.02Section 2 Check

52 Question 3 The first step in the Calvin cycle is the ________.A. replenishing of ribulose biphosphateB. production of phosphoglyceraldehydeC. Splitting of six-carbon sugar into two three-carbon moleculesD. Bonding of carbon to ribulose biphosphateNC: 4.02Section 2 Check

53 The answer is D. The carbon atom from CO2 bonds with a five-carbon sugar to form an unstable six-carbon sugar. This molecule then splits to form two three-carbon molecules.NC: 4.02Section 2 Check

54 Question 4How many rounds of the Calvin cycle must occur in order for one molecule of PGAL to be transferred to the cell’s cytoplasm?A. 1B. 2C. 3D. 4NC: 4.02Section 2 Check

55 The answer is C. Each round of the Calvin cycle produces two molecules of PGAL.Section 2 Check

59 Section 9.3 Summary – pages 231-237GlycolysisGlycolysis is a series of chemical reactions in the cytoplasm of a cell that break down glucose, a six-carbon compound, into two molecules of pyruvic acid, a three-carbon compound.4ATP2ADP2 Pyruvic acid2ATP4ADP + 4PGlucose2PGAL2NAD+2NADH + 2H+Section 9.3 Summary – pages

61 Section 9.3 Summary – pages 231-237GlycolysisBefore citric acid cycle and electron transport chain can begin, pyruvic acid undergoes a series of reactions in which it gives off a molecule of CO2 and combines with a molecule called coenzyme A to form acetyl-CoA.Mitochondrial membraneCO2Outside the mitochondrionInside the mitochondrionCoenzyme A- CoAPyruvic acidPyruvic acidIntermediate by-productAcetyl-CoANAD+NADH + H+Section 9.3 Summary – pages

62 Section 9.3 Summary – pages 231-237The citric acid cycleThe citric acid cycle, also called the Krebs cycle, is a series of chemical reactions similar to the Calvin cycle in that the molecule used in the first reaction is also one of the end products.For every turn of the cycle, one molecule of ATP and two molecules of carbon dioxide are produced.Section 9.3 Summary – pages

65 Section 9.3 Summary – pages 231-237The citric acid cycleFormation of CO2 A molecule of CO2 is formed, reducing the eventual product to a five-carbon compound. In the process, a molecule of NADH and H+ is produced.NAD+NADH + H+O==O(CO2)Section 9.3 Summary – pages

66 Section 9.3 Summary – pages 231-237The citric acid cycleFormation of the second CO2 Another molecule of CO2 is released, forming a four-carbon compound. One molecule of ATP and a molecule of NADH are also produced.NAD+NADH + H+O==OADP +(CO2)ATPSection 9.3 Summary – pages

67 Section 9.3 Summary – pages 231-237Recycling of oxaloacetic acid The four-carbon molecule goes through a series of reactions in which FADH2, NADH, and H+ are formed. The carbon chain is rearranged, and oxaloacetic acid is again made available for the cycle.The citric acid cycleNADH + H+NAD+FADFADH2Section 9.3 Summary – pages

70 Section 9.3 Summary – pages 231-237FermentationDuring heavy exercise, when your cells are without oxygen for a short period of time, an anaerobic process called fermentation follows glycolysis and provides a means to continue producing ATP until oxygen is available again.Section 9.3 Summary – pages

71 Section 9.3 Summary – pages 231-237Lactic acid fermentationLactic acid fermentation is one of the processes that supplies energy when oxygen is scarce.In this process, the reactions that produced pyruvic acid are reversed.Two molecules of pyruvic acid use NADH to form two molecules of lactic acid.Section 9.3 Summary – pages

72 Section 9.3 Summary – pages 231-237Lactic acid fermentationThis releases NAD+ to be used in glycolysis, allowing two ATP molecules to be formed for each glucose molecule.The lactic acid is transferred from muscle cells, to the liver that converts it back to pyruvic acid.Section 9.3 Summary – pages

74 Section 9.3 Summary – pages 231-237Comparing Photosynthesis and Cellular RespirationTable 9.1 Comparison of Photosynthesis and Cellular RespirationPhotosynthesisCellular RespirationFood synthesizedFood broken downEnergy from sun stored in glucoseEnergy of glucose releasedCarbon dioxide taken inCarbon dioxide given offOxygen given offOxygen taken inProduces sugars from PGALProduces CO2 and H2ORequires lightDoes not require lightOccurs only in presence of chlorophyllOccurs in all living cellsSection 9.3 Summary – pages

75 Question 1What do the Calvin cycle and the Citric acid cycle have in common?A. The molecule used in the first reaction is also one of the end products.B. Both require input of ATP molecules.C. Both generate ADP.D. From every turn of the cycle, two molecules of carbon dioxide are produced.NC: 4.02Section 3 Check

76 The answer is A. In the Calvin cycle, RuBP bonds to carbon in the first step and is produced in the last step. In the citric acid cycle, oxaloacetic acid reacts in the first step and is recycled in the last step.NC: 4.02Section 3 Check

84 The Need for EnergyATP is the molecule that stores energy for easy use within the cell.ATP is formed when a phosphate group is added to ADP. When ATP is broken down, ADP and phosphate are formed and energy is released.Green organisms trap the energy in sunlight and store it in the bonds of certain molecules for later use.Chapter Summary – 9.1

85 The Need for EnergyOrganisms that cannot use sunlight directly obtain energy by consuming plants or other organisms that have consumed plants.Chapter Summary – 9.1

86 Photosynthesis: Trapping the Sun’s EnergyPhotosynthesis is the process by which cells use light energy to make simple sugars.Chlorophyll in the chloroplasts of plant cells traps light energy needed for photosynthesis.The light reactions of photosynthesis produce ATP and result in the splitting of water molecules.Chapter Summary – 9.2

87 Photosynthesis: Trapping the Sun’s EnergyThe reactions of the Calvin Cycle make carbohydrates using CO2 along with ATP and NADPH from the light reactions.Chapter Summary – 9.2

88 Getting Energy to Make ATPIn cellular respiration, cells break down carbohydrates to release energy.The first stage of cellular respiration, glycolysis, takes place in the cytoplasm and does not require oxygen.The citric acid cycle takes place in mitochondria and requires oxygen.Chapter Summary – 9.3

90 Although both processes use electron carriers and form ATP, they accomplish quite different tasks as shown in the table.Table 9.1 Comparison of Photosynthesis and Cellular RespirationPhotosynthesisCellular RespirationFood synthesizedFood broken downEnergy from sun stored in glucoseEnergy of glucose releasedCarbon dioxide taken inCarbon dioxide given offOxygen given offOxygen taken inProduces sugars from PGALProduces CO2 and H2ORequires lightDoes not require lightOccurs only in presence of chlorophyllOccurs in all living cellsNC: 4.02Chapter Assessment

91 D. ribulose biphosphateQuestion 2Choose the word from this list that does NOT belong with the others.A. oxaloacetic acidB. FADH2C. Acetyl-CoAD. ribulose biphosphateNC: 4.02Chapter Assessment

92 The answer is D. RuBP is utilized in the Calvin cycle; the others are part of the citric acid cycle.Chapter Assessment

100 The answer is B. Pigments are arranged within the thylakoid membranes in photosystems; the most common pigment is chlorophyll.NC: 4.02Chapter Assessment

101 Question 7Which of the following is a product of cellular respiration?A. lactic acidB. alcoholC. glucoseD. carbon dioxideNC: 4.02Chapter Assessment

102 The answer is D. Carbon dioxide, water, and ATP are the products of cellular respiration.NC: 4.02Chapter Assessment

103 which takes place in stromaQuestion 8Complete the concept map using the following terms: RuBP replenishing, formation of 3-carbon molecules, Calvin cycle, carbon fixation.123are steps in4which takes place in stromaNC: 4.02Chapter Assessment

104 Completed concept map should reflect carbon fixation, RuBP replenishing, and formation of 3-carbon molecules as steps in the Calvin cycle which takes place in stroma.NC: 4.02Chapter Assessment

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